Quotation mark in README.md WebDAV example (AsyncHttpClient#1553)

Some minor fixes in examples code to make them compilable.

Author: sarxos

README.md

@@ -263,8 +263,10 @@ Response response = c.executeRequest(mkcolRequest).get();
 or
 
 ```java
-Request propFindRequest = new RequestBuilder("PROPFIND").setUrl("http://host:port).build();
-Response response = c.executeRequest(propFindRequest, new AsyncHandler(){...}).get();
+Request propFindRequest = new RequestBuilder("PROPFIND").setUrl("http://host:port").build();
+Response response = c.executeRequest(propFindRequest, new AsyncHandler() {
+  // ...
+}).get();
 ```
 
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